There has always been a suspicion in politics that when it comes to big TV interviews prime ministers get treated like leaders while opposition parties get treated like losers.

And research commissioned by MediaGuardian.co.uk shows that while they do not get treated with kid gloves, prime ministers do indeed get treated differently.

Although the BBC's resident rottweiller, Jeremy Paxman, did not give Tony Blair an easy ride on Newsnight, according to research by Loughborough University he focused far more on strict policy issues when interviewing the PM than when talking to William Hague.

Paxman began the interview by repeatedly pressing Mr Blair to admit he had failed to live up to a manifesto promise to sort out the NHS within five years.

He went on to challenge him on schools, taxation and inequality - with the interviewer giving the prime minister a particularly hard time on this last point.

In fact, stopwatch research shows that 21 minutes of the 30-minute Blair interview were spent on policy - leaving just nine minutes or 32% of his exchanges, for personality issues.